Combined hydrotreating process and configurations for same

ABSTRACT

At least two feedstocks ( 210 A) ( 210 B) with different boiling point ranges are hydrotreated in an integrated hydrogenation plant ( 200 ) using an interbed separator ( 240 ) that is fluidly coupled between two hydrogenation reactors ( 230 A) ( 230 B). Contemplated configurations and methods will significantly reduce construction and operating cost by integration of at least two hydrogenation processes of two different feedstocks into one process, and/or by providing process conditions that reduce use of catalyst in at least one of the reactors.

FIELD OF THE INVENTION

[0001] The field of the invention is petrochemistry, and particularlyhydrotreating of various hydrocarbonaceous feedstocks.

BACKGROUND OF THE INVENTION

[0002] Hydrotreating is a type of hydroprocessing commonly used in manymodern refineries, in which hydrogen is contacted in the presence of acatalyst with a hydrocarbonaceous feedstock to remove impurities,including oxygen, nitrogen, sulfur, and to saturate hydrocarbons. Afrequently employed form of hydrotreating is hydrodesulfurization, whichis used primarily to reduce the sulfur content from refineryintermediate streams. Hydrodesulfurization is typically used incombination with processes including feed pretreatment of catalyticreformers, fluidized-bed catalytic crackers, and hydrocrackers, and mayalso be used independently as a product quality improvement step fornaphtha, diesel, jet, heating oil and residues, saturation of olefins,and polycyclic aromatics. Hydrocracking is another type ofhydroprocessing commonly used in many modern refineries, in whichhydrogen is contacted in the presence of a catalyst with ahydrocarbonaceous feedstock to produce lighter products (i.e., theaverage molecular weight decreases). There are numerous hydroprocessingconfigurations and processes known in the art, and continuous efforts toreduce energy consumption and capital cost, while improving productquality, has led to integration of hydrotreating and hydrocrackingreactors in various processes.

[0003] For example, in one integration concept, a hydrotreater iscombined with a hydrocracker as disclosed in U.S. Pat. No. 3,328,290 toHengstebeck that describes a two-stage hydrocracking process whereinfresh feedstock is combined with effluent from the hydrocracking stageand the combined streams are then introduced into a hydrotreating stage.A higher-boiling fraction is then separated from the hydrotreatereffluent and fractionated to produce a light product and a heavierbottoms stream, which is then recycled with hydrogen-containing gas backto the hydrocracking stage.

[0004] Another example U.S. Pat. No. 6,235,190 to Bertram describes anintegrated hydrotreating and hydrocracking process in which twohydrotreating catalysts of different activities are operated in seriesto provide improved product quality, wherein the effluent from ahydrotreating reactor is subjected to a hydrocracking process to convertthe hydrotreated effluent to lighter products with a reduced aromatichydrocarbon content. In a further example, U.S. Pat. No. 6,261,441 toGentry et al., a combined hydrotreating/hydrocracking process isdescribed in which a hydrocracking stage is followed by a hydrodewaxingstage with a single feedstock and a bottoms fraction recycle to producea naphtha product, a distillate boiling above the naphtha range, and alubricant product.

[0005] In yet another system, as described in U.S. Pat. No. 6,328,879 toKalnes, two independent feedstocks are hydrocracked in a catalytichydrocracking process that employs a hydrocracking zone, a hydrotreatingzone, and a high pressure product stripper to produce various products,wherein the products have a lower boiling point range than thefeedstocks.

[0006] Alternatively, more than one hydrotreater reactor, and orcatalyst beds may be employed for catalytic hydrogenation as describedin U.S. Pat. No. 3,537,981 to Parker, or U.S. Pat. No. 6,103,105 toCooper. While Parker's process employs a first hydrotreating reactorcoupled to a separator that is in series with a second hydrotreatingreactor, Cooper et al. employ two serially connected hydrotreatingcatalyst beds without the use of a separator. However, both Coopers andParkers hydrotreating configurations are typically limited to only asingle feedstock.

[0007] Thus, although many integrated processes have provided at leastsome advantage over other known configurations and methods, all oralmost all of the known configurations and methods are limited toprocesses in which hydrocracking is the objective, or in whichhydrotreating of a single boiling range (e.g., naphtha, diesel, gasoil,resid) feedstock is considered. Consequently, all or almost all of theknown hydrotreating processes require separate plants where more thanone feedstock is employed. Therefore, there is still a need to provideimproved configurations and methods for hydrotreating of petroleumproducts.

SUMMARY OF THE INVENTION

[0008] The present invention is directed to configurations and methodsfor hydroprocessing plants, and especially for integrated hydrotreatingplants in which at least two feedstocks with different boiling pointranges (e.g., gas oil and diesel oil) are hydrotreated. Furtherespecially contemplated aspects include methods for controllingcontemplated configurations.

[0009] In one aspect of the inventive subject matter, contemplatedplants include an interbed separator that receives a first feed (e.g.,hydrotreated gas oil) and a second feed (e.g., diesel oil), wherein thefirst feed preheats and vaporizes at least part of the second feed,thereby producing a preheated and at least partially vaporized secondfeed, and wherein at least a portion of the first feed is provided by afirst hydrotreating reactor, and wherein at least a portion of thepreheated and at least partially vaporized second feed is fed into asecond hydrotreating reactor that produces a product.

[0010] Especially contemplated interbed separators include at least apartial vapor liquid equilibrium stage, preferably at least two vaporliquid equilibrium stages, and may have a configuration of a trayedcolumn or a packed column. It is further preferred that contemplatedinterbed separators may receive a hydrogen rich stream, which may berecycled in the plant, and/or which may be a makeup hydrogen stream.Contemplated interbed separators are typically operated at a pressuresimilar to the operating reactor pressure of about 500 psi to about 2400psi.

[0011] In particularly preferred aspects of the inventive subjectmatter, at least a portion of the second feed is fed into the secondhydrotreating reactor, at a rate effective to control light-end recoveryof the hydrotreated first feed in the interbed separator. The remainingportion of the second feed may then be employed to regulate atemperature in the second hydrotreating reactor.

[0012] In another aspect of the inventive subject matter, first andsecond hydrotreating reactors are operated at conditions under which thehydrotreating reactor feed will exhibit less than 10% conversion, andmore preferably less than 8% conversion. Thus, contemplated secondhydrotreating reactors are preferably operated at a pressure of betweenabout 700 psi and about 2400 psi.

[0013] Furthermore, it is contemplated that configurations according tothe inventive subject matter may be realized in a new plant. However,the interbed separator and the second hydrotreating reactor may also beintegrated as an upgrade into an existing hydroprocessing plant.

[0014] In a further aspect of the inventive subject matter, a method ofhydrotreating includes one step in which a first hydrotreating reactor,a second hydrotreating reactor, and an interbed separator that receivesa first feed and a second feed are provided. In another step, theinterbed separator is fluidly coupled to the first and secondhydrotreating reactors. In a still further step, the hydrotreated firstfeed is used to preheat and vaporize at least part of the second feed,thereby producing a preheated and at least partially vaporized secondfeed, and in another step, at least a portion of the preheated and atleast partially vaporized second feed is mixed with another part of thesecond feed and fed into the second hydrotreating reactor.

BRIEF DESCRIPTION OF THE DRAWING

[0015]FIG. 1 is a schematic view of an exemplary configuration of aprior art hydrotreating plant.

[0016]FIG. 2 is a schematic view of an exemplary configuration of ahydrotreating plant according to the inventive subject matter.

[0017]FIG. 3 is a schematic detail view of streams relating to theinterbed separator according to the inventive subject matter.

DETAILED DESCRIPTION

[0018] Various known configurations and processes for desulfurationand/or denitrification utilize a process that employs a hydrotreatingreactor in which a hydrocarbonaceous feed is reacted with hydrogen inthe presence of a catalyst to form H₂S and/or NH₃ from sulfur-and/ornitrogen-containing compounds in the feedstock. Prior Art FIG. 1 depictsa typical configuration 100 for such plants. Here, a single feedstock(e.g., diesel) 110 is passed through a heater 120 and subsequently fedinto a hydrotreating reactor 130. Hydrogen (separately [via line 141],or in combination [via line 142] with the feedstock) is added to thecatalyst in the hydrotreating reactor and the hydrotreated product 112is (after a cooling step in cooler 180) separated in separator 150 intoa gaseous portion 112A, which predominantly comprises hydrogen, hydrogensulfide, and light non-condensable hydrocarbons and a liquid portion112B, which comprises hydrotreated diesel, some wild naphtha, andremaining sour gas. The hydrogen from the gaseous portion is typicallypurified in an absorber 152 with an amine-containing solvent, andrecycled (supra) into the hydrogen reactor via compressor 160. Thehydrotreated product 112C can then be retrieved from column 170 alongwith typical products such as wild naphtha 112D and sour gas 112E. Whilesuch configurations work relatively well for a single type of feedstock(e.g., vacuum gas oil, gas oil, diesel, naphtha, etc.), known plantswith multiple feedstocks (e.g., gas oil and diesel) generally requiremultiple and separate hydrotreating configurations, which addsignificant cost to construction and operation of such plants.

[0019] In their efforts to improve configurations and methods forhydrotreating hydrocarbonaceous feeds, the inventors have discoveredthat multiple feedstocks (ie., feedstocks with different boiling pointranges—e.g., gas oil and diesel) can be hydrotreated in an integratedconfiguration, in which an interbed separator is fluidly coupled to afirst and a second hydrotreating reactor, and in which a single hydrogenrecycling loop (e.g., comprising a cooler or heat exchanger, aliquid/gas separator, an amine stripper, and a compressor) can beemployed for two (or more) hydrotreating reactors each treatingdifferent feeds.

[0020] Consequently, in a particularly preferred aspect of the inventivesubject matter, a plant may comprise an interbed separator that-receivesa first feed and a second feed, wherein the first feed preheats andvaporizes at least part of the second feed, thereby producing apreheated and at least partially vaporized second feed, wherein at leasta portion of the first feed is provided by a first hydrotreatingreactor, and wherein at least a portion of the preheated and at leastpartially vaporized second feed is fed into a second hydrotreatingreactor that produces a product.

[0021]FIG. 2 depicts an exemplary configuration of a hydroprocessingplant 200, in which two different hydrocarbonaceous feedstocks arehydrotreated using an integrated configuration with a single hydrogenrecycle loop. Here, gas oil 210A (first hydrocarbonaceous feedstock) isheated in heater 220 and then introduced into the hydrotreating reactor230A to produce a hydrotreated product 212 (which is the first feed forthe interbed separator). The hydrotreated product 212 is then fed intothe interbed separator (hot separator) 240. It should be recognized thatthe hydrotreated product 212 may pass through equipment (e.g., heatexchangers, etc.) prior to entering the interbed separator 240. Theinterbed separator 240 also receives diesel feed 210B (the second feedfor the interbed separator, which may be preheated) and which ispreferably at least partially (i.e., at least 10-50%, more typically 50to 80%, most typically, 80 to 100%) in the liquid phase. A vapor feed290, typically hydrogen (or hydrogen-containing) may further be fed intothe interbed separator, wherein the vapor feed may be partially recycledwithin the plant. Alternately, the vapor feed (or hydrogen containingfeed) may be at least in part make-up hydrogen.

[0022] Within the separator the second feed is at least partiallyvaporized (or further vaporized) and heated by direct contact with thehydrotreated product 212. Additionally, the interbed separator 240separates the feeds into products in which the more volatile componentswill exit the separator with the vaporized second feed 201′, and theless volatile components will exit with the somewhat cooled hydrotreatedseparator product 212′. The interbed separator will include at least apartial vapor liquid equilibrium stage, or more preferably two or morevapor liquid equilibrium stages, and may have a configuration of atrayed column or a packed column. The liquid hydrotreated product 212′is then fed into column 270A that separates the liquid hydrotreatedproduct 212′ into treated products including but not limited to gas oil,wild naphtha, and sour gas. The vaporized second feed 210′ is then mixedwith additional diesel feed via line 210B′ and introduced (as combinedsecond feed) into the second hydrotreating reactor 230B, which may ormay not receive additional feed streams. It should be appreciated that aportion of the lighter boiling range components will be recovered fromthe first product 212′ and further hydrotreated in the second reactor.

[0023] The so hydrotreated second feed 210″ (here: mostly hydrotreateddiesel) is then cooled in cooler 280 and separated in separator 250 intoa liquid portion and a gaseous portion (predominantly comprising H₂S,hydrogen, and light non-condensable hydrocarbons). The hydrogen in thegaseous portion can be purified via absorber 252, which may useconventional solvents. The compressor 260 compresses thishydrogen-containing recycle gas stream to a suitable pressure forre-introduction into the system (e.g., at first reactor and/or intofirst feed or feedstock). The liquid portion of the second hydrotreatedfeed 210″ is then fed into column 270B that separates the hydrotreatedproducts into treated products which can include, but are not limitedto, low sulfur diesel, wild naphtha, and sour gas.

[0024] As also used herein, the term “interbed separator” refers to aseparator that is fluidly coupled to at least two hydroprocessingreactors such that the interbed separator receives an at least partiallyhydrotreated first feed and a second feed (which may or may not havebeen previously hydrotreated), wherein first and second feeds havedifferent boiling point ranges (e.g., gas oil and diesel oil).Typically, contemplated interbed separators are operated hot (i.e., 300to 750° F.), and it is especially contemplated that the interbedseparator further may receive a vapor or a hydrogen-containing feed.

[0025]FIG. 3 depicts an especially preferred configuration of thestreams around the interbed separator 340 and the second reactor inwhich a portion 310B′ of the second feed 310B, and an additional thirdfeed 395C is fed to the second reactor (via combined stream 310′),bypassing the interbed separator, to produce a hydrotreated product310″. The rate of the substantially liquid phase stream 310B″ (of thesecond feed) is determined to allow for the desired light end recoveryfrom the first hydrotreated feed stock 312′. The term “light-endrecovery” as used herein refers to the recovery of components in acomponent-mixture, wherein the boiling point of the components is in theupper third, and more typically upper fourth (or even higher) of theboiling point range of the mixture. The remaining portion of the secondfeed stock 310B′ may be additionally preheated in a heat exchanger orheater 310C, before being directed to the second reactor. It should berecognized that the third feed may be any hydrocarbonaceous feedstock,and may include naphtha, jet, diesel, or gas oil boiling range material.It should also be recognized that additional (forth, fifth, etc.) feedstreams can be fed to the second reactor, bypassing the interbedseparator. In this exemplary configuration the third feed stock 395C isCycle Oil from an FCC unit. In this preferred configuration the secondreactor operates at a steady feed rate while allowing for good operatingflexibility in the operation of the interbed separator, and good lightend recovery control. It should also be recognized that the reactor 330Bmay operate in a two-phase (vapor/liquid) or preferably trickle flowregime.

[0026] To maintain a particular inlet temperature to the second reactor330B, the feed temperatures of heated streams 310B′ and/or 395C′ can beadjusted via integrated (using internal streams within the plant orstripping or fractionation sections) or external heat sources. Thisability to adjust the feed temperature of the portion of the feed thatbypasses the interbed separator is especially advantageous, sincedirecting a portion of the feed to the second hydrotreating reactor willresolve difficulties associated with the heat balance (e.g., thehydrogen stream 390 would have to be temperature controlled (e.g., ashot hydrogen stripping gas) to circumvent heat imbalance). The amount ofthe second feed that bypasses the interbed separator (e.g., by directfeeding into the hydrotreater downstream of the interbed separator) willalso depend on the relative volumetric rates of the first and secondreactor feed stocks. As the volumetric rate of the second reactor feedincreases, relative to the first reactor feed, the percentage of thesecond reactor feed bypassing the interbed separator will typicallyincrease.

[0027] Still further, it should be recognized that the portion of thesecond feed (or an alternate third feed) that bypasses the interbedseparator (e.g., via direct feed into the second hydrotreater) may bepreheated or temperature controlled. Consequently, it should berecognized that temperature control of the portion of the second feedmay be employed to control the inlet temperature of the secondhydrotreating reactor over a relatively wide range (e.g., ±75 degreesF.). Therefore, the portion of the second feed that bypasses theinterbed separator may typically be in a range of between about 20 vol%(or less) to about 80 vol % (or more) of the entire volumetric rate ofthe second feed. Most typically, however, the amount of the portion ofthe second feed that bypasses the interbed separator will be about 35-65vol %. Preferably, the additional feeds (third, forth, etc.) will be atleast partially liquid phase (below its dew point, prior to the additionof makeup or recycle gas, if any, at the conditions (temperature andpressure) when first fed into the recycle loop, or when measured at thereactor inlet temperature, and pressure). Thus, it should be recognizedthat in some of the contemplated configurations, and especially in thosein which a portion of the second or third feed are in liquid phase andfed into the second hydrotreating reactor, the second hydrotreatingreactor is operated in a two-phase, or preferably trickle flow regime.

[0028] It should further be especially recognized that in preferredaspects of the inventive subject matter both hydrotreating reactors areoperated under conditions effective to reduce the concentration ofsulfur- and/or nitrogen-containing compounds in the feeds. Consequently,it should be recognized that in preferred configurations both feedstocksare substantially not (L e., less than 10%, more typically less than 8%)converted to lower boiling point products. In particularly preferredaspects, the second feedstock comprises diesel, and the diesel containsafter hydrotreating and column separation less than 50 ppm, morepreferably less than 25 ppm, and most preferably less than 10 ppmsulfur-containing products.

[0029] Thus, contemplated configurations may be employed for productionof two products having different boiling ranges and different productspecifications. For example, an existing gas oil hydrotreating plantupstream of a FCC unit may be upgraded, with relatively low capitalinvestment, to include a second reactor (or reactor section) forproducing high quality low sulfur diesel fuel. It should be especiallyrecognized that in such configurations the required capacity increasefor the existing heater, heat exchanger train and coolers will bemoderate to insignificant since additional heat can leave the system viathe product from the interbed separator to be used as stripper preheat.

[0030] Still further, it should be recognized that the concept ofbypassing a portion of the second feedstock around the interbedseparator (e.g., by feeding into the hydrotreater downstream of theinterbed separator) may also be employed in alternative integratedconfigurations and methods, and especially contemplated alternativeconfigurations include those in which a first hydrocracking reactor isserially coupled to a second hydrotreating reactor (see e.g., U.S. Pat.No. 6,328,879 to Kalnes, incorporated by reference herein).

[0031] Still further, it should be recognized that the concept ofbypassing a portion of the second feedstock around the interbedseparator may also be extended to alternative integrated configurationsand methods, and especially contemplated alternative configurationsinclude those in which a first hydrotreating reactor is serially coupledto a second hydrocracking reactor.

[0032] Among other advantages, adding a fluid portion of the third feedto the second reactor, without passing through an interbed separator,will allow processing of a higher boiling point range material (i.e.similar to the first feedstock) without loss of the higher boiling rangefraction of the third feedstock in a separator. Moreover, potentialdifficulties associated with the heat balance may be reduced, if notentirely avoided.

[0033] It should be especially appreciated that the terms“hydrocracking” and “hydrotreating” are not referring to the same typeof hydroprocess occurring in the reactor. As used herein, the term“hydrocracking reactor” as used herein refers to a reactor in which ahydrocarbon-containing feed is converted to lighter products (i.e., theaverage molecular weight decreases), wherein the term “conversion” or“converted” means that a particular percentage of fresh feed changes tomiddle distillate, gasoline and lighter products (see e.g.,“Hydrocracking Science And Technology” by J. Scherzer and A. J. Gruia;Marcel Decker, Inc.). Thus, contemplated hydrocracking reactors willhave a conversion of at least 15%, more typically at least 30%, and mosttypically at least 50%. In contrast, the term “hydrotreating reactor”refers to a reactor in which a hydrocarbon-containing feed is reactedwith hydrogen in the presence of a catalyst under conditions that (a)result in less than 15% conversion, and more typically less than 10%conversion, and (b) result in the formation of H₂S and/or NH₃ fromsulfur- and nitrogen-containing compounds in the hydrocarbon-containingfeed.

[0034] With respect to the first, second, and third hydrocarbonaceousfeedstocks (210A, 210B, and 395C) it should be appreciated that varioushydrocarbonaceous feedstocks are considered suitable for use herein, andin especially contemplated aspects the first hydrocarbonaceous feedstockcomprises gas oil or any petroleum fraction with a boiling point rangehigher than diesel and the second hydrocarbonaceous feedstock comprisesdiesel, or any fraction with a boiling point range lower than the firstfeedstock. In a still further especially contemplated aspect, the thirdhydrocarbonaceous feedstock may comprise any feedstock regardless ofboiling range. Suitable hydrocarbonaceous feedstocks include crude orpartially purified petroleum fractions, including light gas oil, heavygas oil, straight run gas oil, deasphalted oil, kerosene, jet fuel,cycle oil from an upstream FCC (fluid catalytic cracking) reactor etc.While not limiting to the inventive subject matter, it is generallypreferred that suitable first and second hydrocarbonaceous feedstockshave different boiling point ranges, wherein the first hydrocarbonaceousfeedstock typically has a boiling point range that is higher (at least 5degrees centigrade, more typically at least 10 degrees centigrade, andmost typically at least 25 degrees centigrade as measured from the midvolume boiling point in the boiling point range) than the second boilingpoint range. Suitable first and second feed will typically have at leastone different physicochemical parameter (e.g., molecular composition,boiling point range, etc.). The design rates of the sum of the firstfeedstock to that of the second plus third (plus, fourth, fifth, etc)will typically be such that the sum of the feeds to the first reactor isgreater than the sum of feeds the second reactor. The sum of the feedsrates to the second reactor may typically be in a range of between about25 liquid vol % (or less) when measured at standard conditions to about90 liquid vol % (or more) of the sum of the feed rates to the firstreactor. In the most preferred design the sum of the rates to the secondreactor will be between about 40 liquid vol % to about 80 liquid vol %.

[0035] Suitable interbed separators particularly include hot separators,wherein such hot separators are further configured to receive at leastpart of the second feed and possibly a vapor feed, typically hydrogencontaining, which may or may not be optional. In a particularlypreferred alternative aspect of the inventive subject matter, it iscontemplated that the concentration of the hydrogen in thehydrogen-containing feed may vary substantially, and while the hydrogenconcentration in some configurations may be between about 50 vol % and95 vol % (and even more), the concentration of hydrogen may also belower (e.g., between 1 vol % and 50 vol %), or even be substantiallyzero. In such cases, where the hydrogen containing feed is substantiallyfree from hydrogen (i.e., less than 1 vol %), it is preferred that thestream may predominantly comprise light-end-materials (i e., materialsthat will leave the separator as a gaseous component). It is alsorecognized that the vapor feed may be fed from its source withoutadditional preheat. Typically the vapor source will be from a make-upgas compressor, or from a recycle gas compressor. As such thetemperature of the vapor to the interbed separator can be from 80° F. to350° F., more typically be in the range of 125° F. to 300° F., and mosttypically in the range from 150° F. to 275° F. Addition vapor preheat ispossible and advantageous only to the extent that it may improve theplant thermal efficiency, but may also add additional capital cost.

[0036] It should be especially recognized that suitable interbedseparators are preferably operated at a pressure that is at or close tothe pressure in the first hydrotreating reactor and at a pressure thatis at or above the pressure of the second hydrotreating reactor.Consequently, suitable interbed separators will typically be operated atbetween about 500-2400 psi. However, where suitable it should beappreciated that the pressure may also be less than 700 psi andespecially contemplated lower pressures are generally between 700 to 400psi, and even less. Similarly, where hydrotreating conditions allow,interbed separators may also be operated at a pressure above 2400 psi,and suitable higher pressures include pressures between 2400 to 4000psi, and even higher. Due to the relatively high partial pressure ofhydrogen in the separator (the hydrogen may be hydrogen that is recycledwithin the plant), it is contemplated that the effective hydrocarbonvapor partial pressure is less than 200 psi, and more typically within arange of between about 80 psi to 180 psi, and most typically within arange of between about 30 psi to 150 psi.

[0037] In a particularly contemplated aspect of the inventive subjectmatter, it is contemplated that the interbed separator is operated suchthat the temperature of the hydrogenated product from the firsthydrotreating reactor will evaporate at least part of the second feed.Thus, in especially preferred configurations, the at least part of thehydrogenated product will be in a gaseous, or vapor phase, and at leastpart of the second feed (e.g., at least 50%, more typically at least75%, even more typically at least 85%, and most typically at least 80%or 100%) will be vaporized by the heat of the first feed. Consequently,it should be appreciated that the energy required to operate the secondhydrotreating reactor will predominantly be provided by the heat andpressure of the first hydrotreating reactor.

[0038] With respect to particular temperatures, it is contemplated thatthe first reactor will preferably operate at about 650° F., the interbedseparator will preferably operate at a temperature of between about 650°F. and about 600° F., and the second reactor will preferably operate ata temperature of about 600° F. However, it should be recognized thatdepending on the particular feed of the first and second reactors, thepressures and temperatures may vary accordingly. With respect to thetemperature regulation in the second hydrotreater, it should berecognized that the temperature in the second hydrotreating reactor maybe regulated by feeding at least a portion of the second feed, or anadditional feed to the second reactor.

[0039] Additionally, it should be appreciated that the products from thefirst reactor (i.e., the first feed) preheat and vaporize at least partof the second feed. Consequently, it is contemplated that the soproduced vapor will comprise a portion of one or both feeds (typicallyin the same boiling range), and that the so produced vapor is fed incontemplated configurations to the second reactor (which may contain oneor more catalyst beds). It is also contemplated that the liquid remnantsfrom the interbed separator first feed, somewhat cooled from vaporizingthe second feed, can be fed directly to the first feed product stripperwithout additional stripper preheat. It is also contemplated that anintermediate pressure (a pressure set between the operating pressure ofthe interbed separator, and the pressure of the stripper) flash drum inthe feed stream to the stripper may be included to provide a means forsafely letting down the pressure and to recover dissolved hydrogen fromthe stripper feed. It is also contemplated that the liquid remnants fromthe interbed separator first feed stock may pass through equipment otherthan an intermediate pressure flash drum (e.g., heat exchangers, pumps,etc.), en route to the first feed product stripper.

[0040] By integration of two hydrotreating reactors into contemplatedconfigurations, costs for construction and operation of contemplatedplants will be significantly reduced. For example, it is contemplatedthat the cost for a hydrogen recycle compressor in contemplatedconfiguration will be substantially lower than the cost for twoindependent recycle compressors. Additionally, it is contemplated that acommon set of fractionation columns (herein referred to as a gas plant)designed to separate light hydrocarbon fractions can be used downstreamof the product stripper columns can be installed for substantially lesscost than for two independent gas plants. In yet another aspect of theinventive subject matter, it should be appreciated that the energyrequired to operate the second hydrotreating reactor will predominantlybe provided by the heat and pressure of the first hydrotreating reactor.Consequently, it is contemplated that a second heater for the secondreactor may be omitted.

[0041] Furthermore, it should be recognized that the product of thesecond hydrotreating reactor (here: being lower boiling point material)is well suited to sponge (i.e., at least partially remove) lighthydrocarbon components that are not condensable at typical hydrotreatingoperating conditions (temperatures and pressures). Removing thesenon-hydrogen components from the recycle gas purifies the hydrogen richrecycle gas to the first reactor section. Compounds that will be removed(sponged by the products from the second reactor) from the recycle gasinclude methane, ethane, propane, and butanes. Purification of thehydrogen rich recycle gas will advantageously remove essentially inert,light end components and increase the hydrogen partial pressure therebyreducing the size of the equipment(e.g., reactors), and the amount ofhydrotreating catalyst required.

[0042] In a still further aspect, it should be recognized that byfluidly coupling the first reactor to the second reactor, the secondreactor is operating at a significantly higher pressure than a typicalstandalone design designed only to treat the lighter second feed,thereby significantly reducing the amount of required catalyst for thesecond reactor. This reduction in catalyst amount in the second reactorgreatly offsets the additional costs associated for designing the secondreactor at the higher pressure.

[0043] Dimensions and capacities of contemplated hydrotreating reactorswill typically depend at least in part on the particular feedstock, andthe overall throughput capacity of the hydrogenation plant. Thus, it iscontemplated that all known hydrotreating reactors are suitable for useherein. Consequently, the nature of the catalyst may vary considerably.However, preferred hydrotreating catalysts may include those comprisingcobalt, molybdenum and/or nickel distributed on a carrier (e.g., aluminaextrudate).

[0044] It should also be appreciated that suitable configurations mayinclude additional hydrotreating reactors (i.e., a third reactor, afourth reactor, etc.) and separators, wherein each of the additionalreactors are fluidly coupled to an existing or preceding reactor via aseparator that receives the product of the existing or precedingreactor, and that removes at least one component of an additionalfeedstock for the additional reactor. With respect to the components(e.g., piping, hydrotreating reactor, compressor, heat exchanger, etc.)in contemplated configurations, it is contemplated that all known andcommercially available components may be employed. Furthermore,contemplated configurations may be realized in a new plant, however, itis especially preferred that a separator and a second hydrotreatingreactor are integrated as an upgrade into an existing hydrotreatingplant.

[0045] Consequently, a method of operating a plant may comprise a stepin which a first hydrotreating reactor, a second hydrotreating reactor,and an interbed separator that receives a first feed and a second feedare provided. In a further step, the interbed separator is fluidlycoupled to the first and second hydrotreating reactors. In a stillfurther step, the first hydrotreated feed is used to preheat andvaporize at least part of the second feed, thereby producing a preheatedand at least partially vaporized second feed, and in yet another step,at least a portion of the preheated and at least partially vaporizedsecond feed is mixed with the remaining second feed and is fed into thesecond hydrotreating reactor. With respect to the first and secondhydrotreating reactors, the interbed separator, the feeds andfeedstocks, the hydrotreated product, and the hydrotreated product, thesame considerations as described above apply.

[0046] Thus, specific configurations and methods of improvedhydrotreating have been disclosed. It should be apparent, however, tothose skilled in the art that many more modifications besides thosealready described are possible without departing from the inventiveconcepts herein. The inventive subject matter, therefore, is not to berestricted except in the spirit of the appended claims. Moreover, ininterpreting both the specification and the claims, all terms should beinterpreted in the broadest possible manner consistent with the context.In particular, to terms “comprises” and “comprising” should beinterpreted as referring to elements, components, or steps in anon-exclusive manner, indicating that the referenced elements,components, or steps may be present, or utilized, or combined with otherelements, components, or steps that are not expressly referenced.

What is claimed is:
 1. A plant comprising: an interbed separator thatreceives a first hydrocarbonaceous feed and a second hydrocarbonaceousfeed, wherein the first feed preheats and vaporizes at least part of thesecond feed, hereby producing a preheated and at least partiallyvaporized second feed; wherein the first hydrocarbonaceous feed has ahigher boiling point range than the second hydrocarbonaceous feed; andwherein the at least a portion of the first feed is provided by a firsthydrotreating reactor, and wherein at least a portion of the preheatedand at least partially vaporized second feed is fed into a secondhydrotreating reactor that produces a product.
 2. The plant of claim 1wherein the interbed separator comprises at least a partial vapor liquidequilibrium stage.
 3. The plant of claim 1 wherein the interbedseparator comprises at least two vapor liquid equilibrium stages.
 4. Theplant of claim 1 wherein the interbed separator is a trayed column or apacked column.
 5. The plant of claim 1 wherein the first feed compriseshydrotreated gas oil or cycle oil from a fluid catalytic crackingreactor.
 6. The plant of claim 1 wherein the second feed comprisesdiesel oil or cycle oil from a fluid catalytic cracking reactor.
 7. Theplant of claim 1 wherein the interbed separator father receives ahydrogen containing stream.
 8. The plant of claim 7 wherein the hydrogencontaining stream is recycled in the plant.
 9. The plant of claim 7wherein at least a portion of the hydrogen containing stream is amake-up hydrogen stream.
 10. The plant of claim 1 wherein the interbedseparator is operated at a pressure of between about 500 psi to about2400 psi.
 11. The plant of claim 10 wherein the second hydrotreatingreactor is operated at a pressure of between about 700 psi and about2000 psi.
 12. The plant of claim 1 wherein ay least a portion of thesecond feed is fed into the second hydrotreating reactor.
 13. The plantof claim 1 wherein a third feed is fed to the second hydrotreatingreactor,
 14. The plant of claim 12 wherein the portion of the secondfeed bypasses the interbed separator and regulates a temperature in thesecond hydrotreating reactor.
 15. The plant of claim 12 wherein theportion of the second feed controls recovery of a lighter boiling rangematerial from the hydrotreated first feed in the interbed separator. 16.The plant of claim 1 wherein the interbed separator and the secondreactor are integrated as an upgrade into an existing hydroprocessingplant.
 17. The plant of claim 1 wherein the first hydrotreater receivesa first total feed and the second hydrotreating reactor receives asecond total feed, and wherein the second total feed is between 25 vol %to 90 vol % of the first total feed.
 18. The plant of claimn 1 whereinthe first hydrotreater receives a first total feed and the secondhydrotreating reactor receives a second total feed, and wherein thesecond total feed is between 40 vol % to 80 vol % of the first totalfeed.
 19. A method of hydroireatmg comprising: providing a firsthydrotreating reactor, a second hydrotreating reactor, and an interbedseparator that receives a first hydrocarbonaceous feed and a secondhydrocarbonaceous feed, wherein The first hydrocarbonaceous feed has ahigher boiling point range than the second hydrocarbonaceous feed;fluidly coupling the interbed separator to the first and secondhydrotreating reactors; using the first feed to preheat and vaporize atleast part of the second feed, thereby producing a preheated and atleast partially vaporized second feed; and and feeding at least aportion of the preheated and at least partially vaporized second feedinto the second hydrotreating reactor.
 20. The method of claim 19wherein the first feed comprises a gas oil boiling range material andwherein the second feed comprises a material with a lower boiling rangethan gas oil.
 21. The method of claim 19 wherein the interbed separatoris operated at a pressure of between about 500 psi and about 2400 psi,and wherein the second hydrotreating reactor is operated at a pressureof between about 700 psi and about 2000 psi.
 22. The method of claim 19wherein the second hydrotreating reactor produces a product that spongescomponents from a recycle gas that is created at least in part in thefirst hydrotreating reactor.
 23. A plant comprising: an interbedseparator that receives a first hydrocarbonaceous feed and a secondhydrocarbonaceous feed, wherein the first feed preheats and vaporizes atleast part of the second feed, thereby producing a preheated and atleast partially vaporized second feed; wherein the at least a portion ofthe first feed is provided by a first hydroprocessing reactor, andwherein at least a portion of the preheated and at least partiallyvaporized second feed is fed into a second hydroprocessing reactor thatproduces a product; wherein the first hydrocarbonaceous feed bas ahigher boiling point range than the second hydrocarbonaceous feed; andwherein at least a portion of the second feed is fed into the secondhydroprocessing reactor.
 24. A plant comprising: an interbed separatorthat receives a first hydrocarbonaceous feed and a secondhydrocarbonaceous feed, wherein the first feed preheats and vaporizes atleast part of the second feed, thereby producing a preheated and atleast partially vaporized second feed; wherein at least a portion of thefist feed is provided by a first hydroprocessing reactor, and wherein atleast a portion of the preheated and at least partially vaporized secondfeed is fed into a second hydroprocessing reactor that produces aproduct; wherein the first hydrocarbonaceous feed has a higher boilingpoint range than the second hydrocarbonaceous feed; and wherein a thirdfeed is fed into the second hydroprocessing reactor.